Containers of a polyester as represented by polyethylene terephthalate (PET) feature excellent properties such as transparency, heat resistance, gas-barrier property and the like properties, and have nowadays been extensively used for a variety kinds of applications.
In recent years, on the other hand, it is a mounting demand to reutilize the resources inclusive of the above polyester containers. Therefore, attempts have been made to recover the used containers and to reuse them as the recycled resin for various applications.
Here, many of the contents contained in the packing containers are subject to be degraded with light, as represented represented by some kinds of beverages, medicines, cosmetics and the like. Therefore, these kinds of contents are provided being contained in opaque containers that are formed by using a resin composition of a resin blended with a coloring agent such as pigment. From the standpoint of reutilizing the resources, however, the opaque containers are not desirable since they are blended with coloring agents. In order to impart impart light-shielding property (opaqueness) without using coloring agent, therefore, the present applicant has previously previously proposed foamed bottles having a container wall that is foamed by utilizing a microcellular technology (see, for example, patent documents 1 to 3).